<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>画盒子</title>
</head>
<style>
  .red {
    /* 宽度 */
    width: 100px;
    /* 高度 */
    height: 100px;
    /* 背景色 */
    background-color: red;
  }

  .orange {
    width: 200px;
    height: 200px;
    background-color: orange;
  }
</style>

<body>
  <div class="red">div1</div>
  <div class="orange">div2</div>
</body>

</html>